Line Spacing Effect and Determination of Optimum Spacing, Illustrated by Marmora, Ontario, Magnetic Anomaly

CIM Bulletin, 1955

The airborne magnetometer data of the Marmora iron ore deposit at Marmora, Ontario, have 'been used as an example to show the mapped results obtained by the use of line spacings of from 1 mile to 14 mile. The maps are illustrative of the results which could be obtained from such line spacings for any type of geophysical survey, and they show the probability of 'missing' a feature of economy value if the line spacing is too coarse. The probability equations are given for the crossing of randomly oriented features whose maximum dimension is less than the spacing of the control lines for cilcular, elongate, and rectangular outlines. The equations are P = D/S; P = 2Lj ,.S; P = 2(L+W) / ,.S; P = A/ ,.S; P = (2L(S+T)-L2) j ,.ST; and P (D(S+T-,.D)) j ST, respectively; where P is the p:robability; D is the diameter; L is the length; W is the width; and Sand T are line spacings.
Keywords: Controls, Data, Geological Survey of Canada, iron ore, magnetite, magnetometer, Ore, Ores, Probability, Spacing, Structure, Survey, Surveys